In addition to reducing failure and ensuring optimal performance, adequate freezer management also includes optimizing freezer storage capacity to minimize operating costs. The U.S. Depart­ment of Energy looked at the space efficiency of a 2” cryo box and concluded the following, “For samples under 0.5ml, a cryo box 2” tall full of 2.0ml vials may be enormously wasteful. Consider this arithmetic: A standard 2” cryo box has this total volume: 5 x 13.25 x 13.25 cm = 860ml. With 100 cells per box, each cell has a volume of 8.6ml, therefore a 1.0ml sample is only 12% space efficient, and a 0.2ml sample is only 3% space efficient.”

This calculation shows that energy-saving projects such as man­aging your storage space can reduce the annual operating costs dramatically. One way to optimize freezer capacity is to consider compact storage racks based on the ANSI/SLAS standards, which can significantly increase the num­ber of stored samples. Furthermore, the use of durable tubes with maximal sealing performance can minimize contamination and sample degradation ensuring that valuable samples stored for long term projects are still recoverable years down the road. In addition, selecting an appropriate tube volume that corresponds to the needs of each research project further reduces dead volume and maximizes sample recovery.

Every minute an upright ULT freezer door is open, it takes approximately 10 minutes to recover its temperature back to its initial set point. Keeping a well-organized inventory reduces the time needed to search for an item and decreases temperature fluctuations. In addition, when using compact storage racks based on ANSI/SLAS standards instead of 2” cryo boxes, the number of samples stored can be increased by a maximum of 116%, contributing to a more efficient lab space overall.

Whether you have five ULT freezers or one refrigerator, maximizing your sample storage capacity is a good way to ensure you don’t have to buy another cold storage unit.